To the Editor: In their Research Letter, Dr
De Santis and colleagues1 reported a possible
association of infantile hemangiomas with combined antiretroviral therapy
(CART) during pregnancy. As a control group, the authors identified all pregnancies
in which the mother had contacted a teratology information service. There
are numerous ways, however, in which these groups are not comparable, and
which may thus confound the observed association. First, the control group
was self-selected. Second, infantile hemangiomas are very common. Although
their precise incidence is not known, estimates range from 4% to 10%.2 In addition, the increased frequency found in female
and premature infants3 could easily have
confounded the increase in the group treated with CART.